How to tell if its time to change the chain 101.
1. Does it have any frozen links?
2. Does it make a patterned grinding noise that seems to come and go as speed changes?
3. Once adjusted to spec slack, will hit hold that slack for many, many miles?
4. Is the chain visibly damaged in any way?
5. Is there any abnormal wear patterns that cause concern?
6. Will the clip/rivet stay secure on the master link?
7. Does the chain slack measure "fairly close" if take in 4 different spots on the chain?
8. Do you not like the color of your chain?
9. Is your chain too dirty even after cleaning it very well?
10. Are you jelly that your track buddy has a race chain and you still have the 520?
hahahahahahah
Take a stiff bristled brush and give it a good cleaning, it looks fine to me.